When depositing the first layer of molten metal onto the top of the backing plate between the bottom ends of the rails certain difficulties have been encountered, these difficulties affect the appearance of the weld which is to be made in the field in a very short time. The advancing welding wire used in the root pass has heretofore been moved by a robotic control in a normal weave pattern where the welding wire moves back and forth between the rails as the wire progresses along the backing plate in the bottom of the gap. This procedure causes the arc to blow through the backing plate resulting in irregular undersurface for the root pass and certain malformations in the root pass. Such blow through occurs more easily when the wire is moved too rapidly and pulls away from the weld puddle. As the robotic control moves the electrode in a robotic weave axially along the root of the gap, the arc is not pointed toward the intersection between the end of the rail and the lower backing plate. This further results in certain irregularities at this intersection. This problem is accentuated due to the fact that the backing plate is a relatively thin sheet whereas the two spaced rails are massive pieces of metal. The arc blow through of the backing plate and the inability to actually have a blow through at the intersection between the plate and rail ends has presented substantial inconsistencies in the root pass of the previously performed process. These problems affect the appearance of the root pass which is a disadvantage when attempting to use this new welding process as a replacement for prior butt welding and arc welding processes used in the field.